为什么我在尝试在 dart 上运行时会出错？答案

【问题标题】：Why am I getting an error while trying to run this on dart?为什么我在尝试在 dart 上运行时会出错？
【发布时间】：2021-10-05 09:28:24
【问题描述】：

不能无条件调用运算符“+”，因为接收者可以为空。

var numbers = <int>[1,3,2,5,4];

var initialValue = 10;

void main() {
  var foldNum = numbers.fold(initialValue, (curr, next) => (curr + next));
  print(foldNum);
}

【问题讨论】：

试试这种方式var foldNum = numbers.fold(initialValue, (curr, next) => ((curr as int) + next));或var foldNum = numbers.fold(initialValue, (int curr,int next) => (curr + next));

标签： flutter dart dart-null-safety

【解决方案1】：

指定fold的类型为fold<int>...

var numbers = <int>[1,3,2,5,4];

var initialValue = 10;

void main() {
  var foldNum = numbers.fold<int>(initialValue, (curr, next) => (curr + next));
  print(foldNum);
}

【讨论】：

谢谢..它成功了